Alphonse isidore gravier



(No Model.)

A. I. GRAVIER.

DYNAMO ELECTRIC MAGHINE.

No. 403,836. Patented May 21 1889.

(yzfnessesn Q, 6?,

UNITED STATES PATENT OFFICE.

ALPIIONSE ISIDORE GRAVIER, OF PARIS, FRANCE.

DYNAMO-ELECTRIC MACHINE.

SPECIFICATION forming part of Letters Patent No. 403,836, dated May 21, 1889.

Application filed January 9, 1888. Serial No. 260,184. (No model.) Patented in France January 1'7, 1887, No. 180,954; in Belgium April is, 1887,170. 77,109, and in England April 19, 19,87,110. 5,709.

To all 2071/0727, it may concern:

Be it known that I, ALPHONSE ISIDORE GRAVIER, a citizen of the Republic of: France, residing at Paris, in the said Republic, have invented a certain Improvement in Dynamo- Electric Machines, (which has been patented in France by Patent No. 180,954, dated January 17, 1877; Belgium by Patent No. 77,109, dated April 18,1887; and Great Britain by Patent No. 5,709, dated April 19, 1887,) of which the following specification is a full, clear, and exact description.

This invention relates to dynamo-electrical machines in which the field is strengthened on the side upon which the reaction of the armature tends to lessen the field magnetism.

It consists in certain improvements in the construction of the field-magnets for such machines, the explanation of which will be given hereinafter in connection with the accompanying drawings; and it also consists in an improved machine of the class mentioned,

in which the inducing-wire of the field-magnets approximates in length the induced wire of the armature, so as to utilize to the maximum the materials composing the machine. The advantage of this equality in length of the inducing and induced wires will appear.

from consideration of their relative eiiect on the electro motive force of the machine. Thus the electro-n'iotive 'force in a given machine, other things being equal, is proportional, first, to the inducing magnetic field, or, in other words, to the product of the length of the inducing-wire by the intensity of the current which traverses it, second, to the length of the induced wire; third, to the speed of rotation; and is inversely proportional, first, to the width of the inter-iron space, (that is to say, the distance between the iron of the field-magnet and that of the armature,) and, second, to a coefficient which varies with each kind of machine. Consequently the said electro-motive force may be represented by the equation L t Z c E:.*

f It in which E is the electro-motive force at the brushes; L, the length of the inducing-wire; 2', the intensity of. the inducing-current; 7, the

length of the induced wire exposed to induction; o, the velocity of rotation; f, the interiron space, and 7c the variable coefiicient; and if the sum of L and Z remain constant and the other elements are unchanged E will be the maximum when L I Z. By employing, therefore, a length of induced wire equal to or approximating that of the inducing wire, and said length of inducing-wire so distributed or disposed on a proper field-magnet that the reaction of the armature is neutral ized, a maximum machine is produced. Such a maximum machine is included in the invention as well generally as when embodying the special improvements in construction, which also form part of the invention. It will of course further be understood that these special improvements are not limited to the case where the length of the induced wire approximates that of the inducing-wire, although particularly claimed in that connec-' tion.

In the common form of machine with symmetrically-arranged poles the mass of the field-magnets and the length of inducingwire thereon are made very large in comparison with the mass of the armature and the induced wire thereon, so as to minimize the disturbance of the field through the reaction of the armature thereon.

In the accompanying drawings, which form part of this specification, Figure 1 is a diagram. illustrating the reaction of the armature on field-magnets of the ordinary symmetrical form, and Figs. 2 and 3 are diagrams of the armature and field-magn ets of machines constructed in accordance with the present invention.

In dynamo-electrical machines the tendency of the rotating armature is to deflect the lines of force of the field in the direction in which said armature is rotating and to cause a diminution in the magnetism where it approaches the field-pole and an increase where it leaves the same. This distortion of the field is represented in Fig. 1. To neutralize this eflfect, the normal magnetism of the field is made to diminish gradually in the direction of the armatures rotation by providing the field-magnets with two cores on each side of the armature-11amely, the cores A A on one side and the cores B B, on the side opposite-- and so constructing and winding the said cores that when the current is on, the cores of the same pair are magnetized with like magnetism or polarity but of an intensity diminishing in the direction of the armatures rotation, and by providing beyond the cores A, B, of less magnetism additional polar portions in magnetic connection with the magnetic frame 1 2 3 4 of the machine intermediate said cores A, B, of less magnetism and the highly-magnetized core B A of the succeeding pole.

The additional polar portions may be part of the magnetic frame itself, or may be in the shape of projections formed on or attached to said frame. They may be magnetized solely by their connection with the cores A A, B B,, or may be further magnetized by additional coils. In Fig. 2 the additional polar portions are part of the magnetic frame of the machine,

being formed by prolongations a b of the cores A, B,, which prolongations are fastened at their outer ends to the bases of the cores B B, and A A,, respectively, and constitute a magnetic connecting-yoke between said cores. They are magnetized through this connection.

In Fig. 3 they are formed by a number of.

ditional polar portions of like name, in the direction of the rotation of the armature A B, as indicated by the arrow.

polar portions may be made of cast-iron or of soft iron, or of soft and cast iron. It is preferred, however, to employ an arrangement of soft iron and castiron, now to be described, which constitutes a feature of the invention,j

as well generally as when employed in connection with the other improvements of the present invention, and as well when applied to a' single core as to a number of cores in the same machine. The said arrangement consists in making the field-cores of cast-iron and soft iron (which have different magnetic capacity) and in placing the metal of greater capacity-- namely, the soft iron-in advance, or, in other words, on the side which is first passed by a.

given portion of the armature. In the drawings the soft iron is represented by the portions shaded with oblique lines and the castiron by the unshaded portions of the field-;

magnets. The effect of this arrangement is that even with a single core the magnetism is or may be made to diminish the direction of the armatures rotation.

Other special features of invention consist, first, in making a series of two or more cores of metal having different magnetic capacity,

the core of metal having the greater capacity being in advance. Thus in the drawings the cores A B, being partly of soft iron, are made of metal of greater average capacity than the succeeding cores A, B,, of cast-iron; second, in the employment of cores of different cross section, the smaller cores being in advance, as shown by reference to the cores A B, which are smaller in cross-section than the succeedin g cores A, B, third, in the combination, with coressuch as A, B,, for example, in Fig. 2- on opposite sides of the armature provided with polar prolongations, as a. and b, which project past the armature on oppositesides thereof, of cores, as A and B, with smaller poles and of higher magnetism fixed on the same base in advance of first-mentioned cores; and, fourth, in field-magnets (see Fig. 2) having cores (as A, B,) with their axes of Winding transverse to the armature-axis, and their ends, which are turned toward the armature,

are provided with a prolongation (as a or b) from each core, (A, or B,,) the outer end of said prolongations being fastened to the base of the core (A, or B,) of the succeeding pole and forming a magnetic yoke, as Well as polar portion for distributing the field-magnetism to the armature, and the prolongations from the two cores lying on opposite sides of the armature. This last feature is included in the invention, as well irrespective of the cores A B as in connection therewith. It gives, in a very simple way, the gradual diminution of the normal magnetism whereby the reaction of the armature is counteracted.

The other special features recited are also of advantage in connection with the production of a field-pole Whose normal magnetism 1 diminishes in the direction of the armatures The cores AA, B B, and the additional rotation.

In order to produce a maximum machine,

or machine which will utilize to the maximum the Wire employed in its construction, the inducing-wire on the cores A B A, B,, or on said cores and the additional polar projections, as A A, B B,,, is made of approximately the same length as the induced wire of the armature A, B, and suitably distributed on the field-cores, or field-cores and additional polar portions as to induce a field whose normal magne ism gradually diminishes in the direction of the armatures rotation.

I claim as my invention or.discovery 1. In combination with the rotatory armature of a dynamo-electrical machine, field-m agnet-s provided on each side of said armature with two electro-magnetic cores of unequal magnetism and additional polar portions of less magnetism than either of said cores arranged after them in the direction of the armatures rotation, the cores of higher magnetism being in advance of the other cores and the said additional polar portions being magnetically connected with the magnetic frame of the machine intermediate the said cores of less magnetism of one pole and the bases of the more highly-magnetized cores of the succeeding pole, substantially as described.

2. In combination with the rotatory armature of a dynamo-electric machine, field-magnets provided with cores composed of two metals of unequal magnetic capacity, as soft iron and cast-iron, with the metal of greater capacity in advance, substantially as described.

3. In combination with the rotatory armature of a dynamo-electrical machine, field-magnets provided with cores or polar portions of like polarity, made of metal of different magnetic capacity, the core or polar portion whose metal is of greater capacity being in advance, substantially as described.

4. In. combination with the rotatory armature of a dynamo-electric machine, fieldmagnets provided with cores of like polarity differing in cross-section and arranged with smaller cores in advance of the larger core or cores of the same polarity, substantially as described.

5. In combination with the rotatory armature of a dynamo-electrical machine, field-magn ets of which the last, taken in the direction of the armatures rotation, is provided with a polar prolongation extending in the same direct-ion preceded by a core with a smaller polar portion and of higher magnetism, sub stantially as described.

6. In combination with the rotatory armature of a dynamo-electri cal machine, field-magnets having cores with their axes of winding transverse to the armature-axis and their polar ends turned toward the armature and provided with a prolongation extending from one side of a core of each pole and fastened at its outer end to the base or bases of the core or cores of the opposite pole, the prolongations lying on opposite sides of the armature and forming a magnetic yoke or frame of the machine, as well as polar portions for distributing field magnetism to the armature, substantially as described.

7. The improved dynamo-electrical machine provided with field-magnets whose normal magnetism diminishes in the direction of the armatures rotation and which. are excited with said normally-diminishing magnetism by inducing-wire substantially equal in length to the induced wire of the armature, substantially as described.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

ALPI-IONSE ISID ORE GRAVIER.

Vitnesses:

O. GIRALY, J. B. BOURNE. 

